387 research outputs found

    Kharkiv region of Ukraine in the aspect of a polycentric development model

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    This article is devoted to the analysis of a model of regional development of Kharkiv region of Ukraine, which is monocentric, and the rationale for the formation of polycentrism in the region. The city of Kharkiv and urban areas as centers of growth in the region are considered in the articl

    Transport properties of the azimuthal magnetorotational instability

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    The magnetorotational instability (MRI) is thought to be a powerful source of turbulence in Keplerian accretion disks. Motivated by recent laboratory experiments, we study the MRI driven by an azimuthal magnetic field in an electrically conducting fluid sheared between two concentric rotating cylinders. By adjusting the rotation rates of the cylinders, we approximate angular velocity profiles ω ∝ r q . We perform direct numerical simulations of a steep profile close to the Rayleigh line q & −2 and a quasiKeplerian profile q ≈ −3/2 and cover wide ranges of Reynolds (Re ≤ 4 · 104 ) and magnetic Prandtl numbers (0 ≤ Pm ≤ 1). In the quasi-Keplerian case, the onset of instability depends on the magnetic Reynolds number, with Rmc ≈ 50, and angular momentum transport scales as √ PmRe2 in the turbulent regime. The ratio of Maxwell to Reynolds stresses is set by Rm. At the onset of instability both stresses have similar magnitude, whereas the Reynolds stress vanishes or becomes even negative as Rm increases. For the profile close to the Rayleigh line, the instability shares these properties as long as Pm & 0.1, but exhibits a markedly different character if Pm → 0, where the onset of instability is governed by the Reynolds number, with Rec ≈ 1250, transport is via Reynolds stresses and scales as Re2 . At intermediate Pm = 0.01 we observe a continuous transition from one regime to the other, with a crossover at Rm = O(100). Our results give a comprehensive picture of angular momentum transport of the MRI with an imposed azimuthal field

    GEOGRAPHICAL ANALYSIS OF FOREST FLORA OF THE CENTRAL CISCAUCASIA

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    Abstract. Aim. Forest flora of the Central Ciscaucasia in General is a relict, geographically situated in the steppe zone. Composing flora elements have different types of habitats, concentrated in the natural physical-geographical unit where isolated from the main habitats. Comparative analysis of the geographic, ecological and systematic components of forest flora will provide data about the correlation of these parameters identify the leading group. Location. The Central CiscaucasiaMethods. We made the geographical and systematic ranges of forest flora of the Central Ciscaucasia and their comparative analysis is conducted.Results. Geographical analysis of forest flora of the Central Ciscaucasia revealed 16 geographical elements, grouped in 6 categories, among which is the predominant group of boreal geographical elements. It is established that the leading geographical elements are Euro-Caucasian, Caucasian and Sub-Caucasian, numbering 189 species, and are half of the flora. Comparison with ecological spectrum showed that the sequence geographical elements completely different, here leading positions are occupied Northern species as ecologically more conservative, and the Caucasian demonstrate ecological plasticity. In a systematic relation matched warheads geographical and systematic spectra. The scope of the results. The results may be used in comparative Floristics, in its theoretical part in adjusting themodels of the Genesis of the flora.Conclusions. Thus, half of the geographical elements of the forest flora of the Central Ciscaucasia are linked in their distribution of Caucasian floristic province (Euro-Caucasian, Caucasian and Sub-Caucasian). These same geographical elements to predominate in the head part of the spectrum families. Most geographical elements have low ecological plasticity species, their components, do not go beyond the forest plant association, but geographical elements head part of the geographical range are the most ecologically plasticity

    Study of psychological status of tsu students from exercise therapy group

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    The present article contains the results of ascertaining study, aimed at identification of the psychological characteristics of students engaged in groups of exercise therapy. It has been established that students with poor health differ greatly in psychometric characteristics from the group of students who do not have any problems with their health. These differences are most pronounced in the findings obtained by means of questionnaires of constructive thinking and level of subjective control. Students who train in the groups of exercise therapy, need special forms of organization of the educational process involving psychological methods

    Oxygen-conducting Composites Based on Me2(WO4)3 (Me = Sm, Al)

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    Composites Sm2(WO4)3-WO3 and Al2(WO4)3-WO3 were prepared by the solid-state method and a systematic study of their electrotransport properties has been carried out. A sharp increase in the oxygen-ion conductivity is observed in composites Sm2(WO4)3–WO3 at small WO3 values (about 10 mol.%). This effect is probably caused by formation of the non-autonomous interface phase covering grain boundaries of Sm2(WO4)3. These composite O2− – electrolytes are perspective materials for high temperature fuel cells. Тhe composite effect is absent in the Al2(WO4)3–WO3 system. This is probably due to the negative thermal expansion coefficient of Al2(WO4)3, which prevents the formation of a continuous high-conducting microphase film. Keywords: composites, ionic conductivity, heterogeneous doping, microphas

    The formation and development of the managerial personnel reserve on the example of the Tatarstan republic

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    The article describes the practice of formation the personnel reserve in government and administration of the Tatarstan Republic. Also presents an analysis of candidates for inclusion on the roster consisting of three interconnected successive stages- preparatory, competitive and evolving. The authors emphasize the usage of working with a reserve by the structural subdivisions of the human control and power, as well as individual activity types of reservists

    Broad Line Emission in Low-Metallicity Blue Compact Dwarf Galaxies: Evidence for Stellar Wind, Supernova and Possible AGN Activity

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    We present spectra of a large sample of low-metallicity blue compact dwarf galaxies which exhibit broad components in their strong emission lines, mainly in Hbeta, [O III]4959, 5007 and Halpha. Twenty-three spectra have been obtained with the MMT, 14 of which show broad emission. The remaining 21 spectra with broad emission have been selected from the Data Release 5 of the Sloan Digital Sky Survey. The most plausible origin of broad line emission is the evolution of massive stars and their interaction with the circumstellar and interstellar medium. The broad emission with the lowest Hα\alpha luminosities (10^36 - 10^39 erg/s) is likely produced in circumstellar envelopes around hot Ofp/WN9 and/or LBV stars. The broad emission with the highest Halpha luminosities (10^40 - 10^42 erg/s) probably arises from type IIp or type IIn supernovae (SNe). It can also come from active galactic nuclei (AGN) containing intermediate-mass black holes, although we find no strong evidence for hard non-thermal radiation in our sample galaxies. The oxygen abundance in the host galaxies with SN candidates is low and varies in the range 12 + log O/H = 7.36 - 8.31. However, type IIn SN / AGN candidates are found only in galaxies with 12 + log O/H < 7.99. Spectroscopic monitoring of these type IIn SN / AGN candidates over a time scale of several years is necessary to distinguish between the two possibilities.Comment: 50 pages, 6 figures. Accepted for publication in the Astrophysical Journa
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